## Advertising

-----Original Message----- From: Bruno Marchal <[EMAIL PROTECTED]> To: [EMAIL PROTECTED] Cc: everything-list@eskimo.com Sent: Sat, 27 Aug 2005 14:31:08 +0200 Subject: Re: subjective reality >[BM]

`>I do think so. See Deutsch book which make clear that the MWI is`

`based on comp. But it is explicit in Everett and in Wheeler`

`>assessment. From a strict logical point of view, ad hoc non comp`

`theory of MWI can be built but it is really out of topic.`

[GK]

`> That may be Deutsch's opinion (though, again, I doubt he says`

`anything like that in his book) but I have read both`

`> Everett's thesis and both Wheeler's and DeWitt's defenses of it and`

`in no way shape or form does anything like YD`

>even figure in them!!! [BM]

`Literally, of course. YD is just a tools for explaining what it is "to`

`be like an Everett memory machine". It is implicit in reducing the`

`quantum uncertainty to the ignorance of which branch we are in a`

`superposition. Mathematically it can be justified by Gleason theorem or`

`by Graham Hartle type of infinite "frequency" operator. See the`

`Preskill's course on quantum computation which makes a nice summary.`

[GK]

`I don't quite know what you mean by an "Everett memory machine"`

`neither could I find a definition (or a mention of it) in Preskill's`

`lectures. If by this you mean something like a machine whose memory`

`would track the successive branchings such`

`thing is innimical to the Everett notion that all information`

`contained in the universal wave function is relative and all`

`probabilities`

`are conditional. Otherwise all "memory machines" are either (1)`

`classical and thus relativised to one branch or (2) quantal and`

`permanently standing in a superposition of branches so that their`

`memories would be as "un situated" as that of any other`

`subject. As for your "justification" I will just quote Preskill on a`

`piece of credo which is characteristic of Many-Worlders:`

`"My own view is that the Everett Interpretation of quantum theory`

`provides a satisfying explanation of measurement and`

`of the origin of randomness, but does not yet fully explain the`

`quantum mechanical rules for computing probabilities. A full`

`explanation should go beyond the frequency interpretation of`

`probability --- ideally it would place the Bayesian view of`

probability on a secure objective foundation."

`Though this is highly disputable in itself I think it shows quite well`

`where your statement above is mistaken.`

>[GK]

`> Let me understand this: your aim is to derive QM from an hypothesis`

`which, you know, is contradicted by QM ?!!!? Wow!`

>I have already answered. [GK] That is a Yes, than. [BM]

`The current aim is to derive SWE (by which I mean the correct`

`geometrical-gravity extension of Schroedinger Wave Equation) from comp.`

`I don't expect to derive anything like SWE + collapse (although this is`

`not entirely excluded!).`

What I have already proved is that

`1) if you make the move from "SWE + collapse" to "SWE + comp", then`

`from purely arithmetical reasons you are forced to go the the quite`

`simpler theory "comp". This is the result of the UDA reasoning and you`

`are invited to criticize it: it presuppose some "folk-psychology" and`

`some passive understanding of Church thesis. See the slide of my 2004`

`SANE paper for a presentation is eight steps.`

`2) I translate that reasoning into the language of a large class of`

`universal machine and got more constructive description of the physics`

`you need (by "1)") to derive from comp. This is technically more`

`involved. It suppresses the need of the folk psychology.`

Bruno [GK]

`I decrypt the above as a statement that you are NOT trying to derive`

`QM but a more general TOE, so that assuming YD is no`

`different than say, assuming subplankian determinism like 't Hooft or`

`Hiley do. I guess you need a lot more good luck than I first wished`

`you!`

`Because you referred me to Deutsch's book I too a look at his own`

`defense of the Everett interpretation and was reminded also`

`of his not so passive understanding of the CT. As it turns out his`

`whole masterplan hinges on his belief that *CT is a result of`

Physics* so he is really no great help to you. Best regards, Godfrey ________________________________________________________________________

`Check Out the new free AIM(R) Mail -- 2 GB of storage and`

`industry-leading spam and email virus protection.`